Development of Transfer JET has advanced as a proximity wireless communication system between two communication devices which are in proximity to each other to form a gap of approximately several cm therebetween.
To perform communication by utilizing this type of proximity wireless communication system, coupler apparatuses having two communication devices mounted thereon, respectively, are proximally positioned to face each other. Each coupler apparatus includes a coupling element and utilizes electromagnetic coupling between the coupling elements to transmit or receive electromagnetic waves.
In general, a coupler apparatus is constituted by arranging a coupling element and a ground plane, each of which is obtained by forming a conductive material into a tabular shape, to face each other. Further, in the coupler apparatus on a transmission side, an electromagnetic field is generated around the coupler apparatus by feeding a signal to a portion between the coupling element and the ground plane to generate an electric current in the coupling element, thereby producing electromagnetic coupling between this coupler apparatus and a coupler apparatus on a reception side. In the coupler apparatus on the reception side, the above-described signal can be fetched as a potential difference between the coupling element and the ground plane when the electric current is generated in the coupling element based on the produced electromagnetic coupling.
Since the coupler apparatus has the above-described principle, the coupling element and the ground plane are arranged in close proximity to each other. Therefore, a part of the electric current flows through the ground plane via a space, and a part of the fed energy becomes a loss without being utilized for the electromagnetic coupling.
Under such circumstances, reducing leakage of the electric current from the coupling element to the ground plane to efficiently improve a degree of coupling has been demanded.